Float measuring device for mercury cells

ABSTRACT

D R A W I N G METHOD FOR DETERMINING THE DISTANCE BETWEEN THE WORKING FACE OF AN ANODE AND A RESERVOIR OF MERCURY BENEATH THE ANODE IN A SUBSTANTIALLY ENCLOSED ELECTROLYTIC CELL HAS A VALUE ESTABLISHED FOR THE POSITION OF THE WORKING FACE OF THE ANODE IN THE CELL ON AN EXTERNAL SCALE MEANS AND ANOTHER VALUE ESTABLISHED FOR THE SURFACE OF THE MERCURY RESERVOIR IN THE CELL ON THE EXTERNAL SCALE MEANS. THE DEPTH OF THE MERCURY RESERVOIR CAN ALSO BE DETERMINED. A MEASURING DEVICE IN AN ELECTROLYTIC CELL HAS A TUBE ATTACHED TO A CAGE ON AN ANODE NEAR AN OPENING IN THE ANODE. THE CAGE FORMS A CHAMBER ABOVE THE OPENING IN THE ANODE AND THE OTHER END OF THE TUBE IS CONNECTED WITH AN OPENING IN THE COVER OF THE ELECTROLYTIC CELL. A FLOAT IS MOVABLY DISPOSED BETWEEN THE CHAMBER AND THE MERCURY RESERVOIR. THE FLOAT FITS INTO THE CHAMBER AND PREFERABLY HAS A HEIGHT EQUAL TO THE HEIGHT OF THE CHAMBER ABOVE THE WORKING FACE OF THE ANODE. THE FLOAT HAS A ROD ATTACHED WHICH EXTENDS THROUGH THE TUBE TO GIVE READINGS ON A SCALE MEANS LOCATED OUTSIDE THE ELECTROLYTIC CELL.

Dec. 12,1972 A. L. BARBATO 3,705,842

FLOAT MEASURING DEVICE FOR MERCURY CELLS FiledNov. 16, 1970 INVENTORALEXANDER L. BARBATO, Deceased by PATRICIA J. BARBATO, ExecufrixATTORNEY United States Patent Othce 3,705,842 Patented Dec. 12, 19723,705,842 FLOAT MEASURING DEVICE FOR MERCURY CELLS Alexander L. Barbato,deceased, by Patricia J. Barbato,

executrix, Perry, Ohio, assignor to Diamond Shamrock Corporation,Cleveland, Ohio Filed Nov. 16, 1970, Ser. No. 89,643 Int. Cl. C01d 1/08;C22d N04 US. Cl. 204-99 17 Claims ABSTRACT OF THE DISCLOSURE Method fordetermining the distance between the working face of an anode and areservoir of mercury beneath the anode in a substantially enclosedelectrolytic cell has a value established for the position of theworking face of the anode in the cell on an external scale means andanother value established for the surface of the mercury reservoir inthe cell on the external scale means. The depth of the mercury reservoircan also be determined. A measuring device in an electrolytic cell has atube attached to a cage on an anode near an opening in the anode. Thecage forms a chamber above the opening in the anode and the other end ofthe tube is connected with an opening in the cover of the electrolyticcell. A float is movably disposed between the chamber and the mercuryreservoir. The float fits into the chamber and preferably has a heightequal to the height of the chamber above the working face of the anode.The float has a rod attached which extends through the tube to givereadings on a scale means located outside the electrolytic cell.

FIELD OF THE INVENTION This invention relates to devices and methods forperforming measurements in operating electrolytic cells by an operatoroutside the cells. In greater detail this invention concerns instrumentscapable of being used to measure the distance from a working face of ananode to a mercury reservoir in an electrolytic cell and the depth ofthe mercury reservoir in the electrolytic cell.

DESCRIPTION OF THE PRIOR ART A recent development in thechlorine-caustic industry is the use of dimensionally stable anodes. Theanodes, as their name implies, have the advantageous property ofconducting current at relatively low chlorine overvoltages whilethemselves exhibiting great resistance to the corrosive environmentpresent in the chlorine-caustic cells. The properties of these anodesafford significant advantages enabling their utilization in mercury-typecells.

in a mercury-type cell using dimensionally stable anodes in theelectrolysis of solutions for the production of chlorine and the like,one of the more important variables is the distance between the workingface of the anode and the surface of the mercury in the cell(hereinafter sometimes referred to as the operating distance). Theoperating distance is important because if the distance is too small,severe short circuits in the system can develop, and if the distance istoo large, there is an increased voltage drop dissipating power in theelectrolytic process.

No methods or devices are currently known for determination by anelectrolytic cell operator of the distance between the surface of amercury reservoir and the working face of a dimensionally stable anodein an electrolytic cell or the depth of the mercury reservoir in theelectrolytic cell. The electrolytic cell involved in this inventioncomprises a lower electrode having a substantially horizontal uppersurface (a mercury layer), an upper electrode having a substantiallyhorizontal lower surface, an electrode vessel having a lid above saidupper electrode, means for adjustably suspending the upper electrode insaid cell and means for operating the suspending means for verticallymoving said upper electrode. Currently, when mercury-type cells areassembled for electrolysis, the working face of the anode is placed onthe cell bottom and then removed from the cell bottom a given distance.The flow of mercury through the cell is started so as to form areservoir of mercury continuously present in the cell with relativevertical adjustment of the working face of the anode for optimumoperating conditions. As can be expected the adjustment is only aseffective as the skill of the operator since the operator has no preciseparameters for the operating distance. It is desirable to be able tomeasure the operating distance between the working face of an anode andthe surface of a mercury reservoir for a given anode setting in anelectrolytic cell so the operating distance is a known number and can bechecked by subsequent measurement. 'It is further desirable to know theoperating distance for a given anode setting as changes in the distancebetween the surface of the mercury in the cell and the working face ofthe anode can occur independently of changes in the anode setting due tochanges in conditions in the mercury-type cells. One of the possiblechanges in an operating cell is the development of mercury butter, amixture of mercury, sodium and iron. The mercury butter can accumulatein the cell raising the mercury level in the cell and changing theoperating conditions of the cell. Unexpected developments andemergencies, such as mercury butter build-ups causing short circuits,can result in the operator making quick movement in the verticalposition of the anode and losing the relative vertical position of theanode in the cell. The foregoing are representative of the manydevelopments during the operation of mercury-type cells which make itdesirable to be able to measure the operating distance between thesurface of the mercury and the working face of the anode and the depthof the mercury reservoir in the electrolytic cell.

SUMMARY OF THE INVENTION It is the principal object of this invention toprovide measuring means for mercury-type electrolytic cells enabling adetermination of the operating distance between the working face of ananode and the surface of a body of mercury in the electrolytic cell andthe depth of the mercury reservoir in the electrolytic cell without anyinterruption or any interference with the operation of the cell. Thesedeterminations may be made by an operator through the use of themeasuring devices disclosed in this invention.

It is a further object of this invention to provide float meanssensitive to a change in the level of a body of mercury in anelectrolytic cell due to changing conditions during operation of theelectrolytic cell.

Other objects and advantages of the invention herein disclosed will beapparent to those skilled in the art from a reading of the followingspecification, the appended claims and by reference to the attacheddrawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 shows a partially cutaway sectionthrough a mercury-type electrolytic cell having a dimensionally stableanode which has connected therewith a measuring device having a cageattached to the anode and a tube which extends outside the cellconnected to the cage and a float with an attached rod partially heldwithin the tube and the rod actuating a scale means positioned outsideof the electrolytic cell.

FIG. 2 shows an alternative scale and pointer combination which can beemployed with the measuring device of the present invention.

FIG. 3A shows a partially cutway top view and FIG. 3B shows a partiallycutaway section along line B-B in FIG. 3A of another embodiment of theinvention in which the chamber above the anode structure has a differentconfiguration and FIG. 3C shows an isometric view of this component.

FIG. 4- shows another embodiment of a float capable of being used inthis invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS This invention presents amethod and associated apparatus for determining the distance between theworking face of an anode having an opening therein and a reservoir ofmercury beneath the anode and the depth of the mercury reservoir in asubstantially enclosed electrolytic cell where a tube or sleeve runsbetween an opening in the cover of the cell and is connected to theanode at a point near the opening in the anode defining a path in thecell with the portion of the tube adjacent the anode forming a chamberover the opening in the anode. The tube can also run between the openingin the cover of the cell and a cage positioned over the opening in theanode with the cage forming a chamber over the opening in the anode.Between the chamber and the mercury reservoir is movably positioned afloat capable of fitting into the chamber and the float preferably beingof height equal to the height of the chamber above the working face ofthe anode. The float has a rod attached thereto which extends throughthe tube and outside the cell to give readings on a scale means mountedon the cover of the cell. The distance between the Working face of ananode and a reservoir of mercury in the electrolytic cell beneath theanode is determined by positioning the float so it is in contact withthe top of the cage or the top of the portion of the tube forming thechamber giving a reading on the scale means and then allowing the floatto ride upon the mercury reservoir in the cell giving another reading onthe scale means. The depth of the mercury reservoir in the electrolyticcell can be determined by manually depressing the float-rod combinationuntil it rests upon the mercury cathode support (cell bottom 13), givinganother reading on the scale means.

Referring now to FIG. 1 there is shown a partially cutaway sectionthrough a mercury-type electrolytic cell having a dimensionally stableanode 10 shown partially cut away with working face 11 receiving powerinput from a source (not shown) through appropriate lead-ins (not shown)and conductor bars (also not shown). The electrolytic cell has cellbottom 13, cell cover 12 and walls (not shown) forming a substantiallyenclosed cell except for opening 15. A mercury reservoir 14 of a givenheight is in the bottom of the cell forming the cathode of the cell. Themesh anode 10 has a circular opening located at, and of diameter equalto, the distance between the two mesh strands labeled 16. Fastened ontoanode 10 is a hollow, cylindrical coupling 17 shown partially cut awaywhich in turn is capped by a plug or bushing 18 also shown partially cutaway which is threadably connected to coupling 17 with opening 32receiving rod 23 therethrough. Hollow cylindrical tube or sleeve 19 isconnected on top of plug 18 and is sealed by seal 20 to cover 12. Plug18, coupling 17 and anode 10 enclose a chamber 22 of height preferablyequal to the height of float 21. If the height of chamber 22 differsfrom the height of float 21 then the differences must be considered inthe determination of the operating distance between the working face 11of anode 10 and the mercury reservoir 14. Float 21 is constructed so itrides on mercury reservoir 14 and has attached thereto rod 23. Thefloat-rod combination is capable of being movably positioned between thechamber 22 adjacent plug 18 and the surface of the mercury reservoir 14.Rod 23 extends through chamber 22, the opening 32 in plug 18, hollowtube or sleeve 19 and outside the cell cover 12 at opening 15 coming incontact with marker 24 which is pivoted on pivot 25 on scale 26. Thefloat-rod combination can be manually raised from its position shown inFIG. 1 riding on the mercury reservoir 14 which changes the position ofpointer 24 on scale 26. Scale 26 is fastened to tube 19 by connectors28.

When rod 23 is manually raised so float 21 is in contact with the bottomof plug 18 in chamber 22, the marker is so positioned that it indicatesa zero or known calibration mark. At this position the bottom of float21 is preferably at the same level as the working face 11 of anode 10since the height of float 21 is preferably equal to the height of cavity22 which is also the distance between the bottom of plug 18 and workingface 11 of anode 10. While this is a preferred embodiment it is to beemphasized that so long as the height of the float 21 and the height ofchamber 22 are known values so that the difference between these heightscan be used in a calculation, the operating distance between the workingface 11 of anode 10 and mercury reservoir 14 can be determined in asimple calculation. When rod 23 is released it moves down tube 19 asfloat 21 moves down from cavity 22 into contact with mercury reservoir14. This results in pointer, 24 following rod 23 to a new reading onscale 26 giving the distance between the working face 11 of anode 10 andthe surface of mercury reservoir 14. Where this distance varies from thedesired distance between the working face 11 of anode 10 and mercuryreservoir 14, the distance is changed by moving anode 10 to a newsetting giving the.

desired operating distance.

This device allows an operator to take rapid measurements of theoperating distance during electrolytic operations by initiallydetermining a reference point when the float 21 is in contact with plug18 to be used as a reference for subsequent readings when the float isriding on the mercury reservoir or establishing a zero point bywithdrawing rod 23 so the top of float 21 is in contact with plug 18.Then the operator allows float 21 to return to riding on mercuryreservoir 14. Where the distance measured varies from that desired, theoperator makes an adjustment of the position of anode 10 in theelectrolytic cell. Such adjustment requires the operator to establish anow reference point for taking subsequent readings when the float 21 isin contact with plug 18.

Tube 19 is so arranged that there is a minimum exposure of personnel tothe electrolytic reaction. It is preferable that tube 19, coupling 17and plug 18 be made of a valve metal such as titanium and tantalum or analloy of a valve metal, although various metals and alloys can be usedif properly coated for corrosion resistance. The cell cover can berubber or steel with a mbber lining on the side exposed to electrolyticreaction, or any commercially available corrosion resistant cell cover,and the construction of the scale is not critical and can be stamped outof steel. The float can be a hollow plastic container or a hollow metalcontainer with a polymeric coating covering the metal to give corrosionresistance, with fluoro' carbon and acrylic polymers being preferred.Especially preferred polymers are polytetrafluoroethylene and methylmethacrylate trade products sold under the names Teflon and Lucite. Thefloat and the rod are made so that their weight is greater than theweight of an equal volume of brine but less than the weight of an equalvolume of mercury. This can be adjusted by adding or removing suitableweights such as lead balls to the float container. In this way the floatwillride on top of a mercury reservoir but will sink in an aqueousmedium. This feature is important in mercury-type electrolytic cells asa brine layer is present on top of the flowing mercury cathode and thefloat must sink in the aqueous brine layer but float on the mercurylayer in order to give an accurate reading of the distance between theworking face of the anode and the mercury layer. The bottom surface ofthe float 21 riding on the mercury reservoir 14 is preferably large insize compared to the size of the upper surface of the float so that nodepression of the float in the mercury occurs. FIG. 4 shows anotherconfiguration for the float 21 in which the bottom has a large surfacearea with the sides sloping toward the rod 23, and grooves 29 on thebottom of the float to prevent formation of a vacuum under the float dueto the flowing mercury. Also the grooves prevent the float from stickingto the cell bottom when it is submerged by manual force in the mercurylayer. The rod is constructed of rigid material (preferably a valvemetal such as titanium or tantalum) so that accurate readings are givenon scale 26 of the position of the float. While the embodiment of thedimensionally stable anode shown in the drawings is of meshconfiguration, any other type of anode such as perforated corrugated orsolid sheets, or rods may be used provided at least one suitable openingis provided to permit passage of the float through the anode into thechamber located above the anode. The dimensionally stable anodecomprises an electrically conductive surface supported by a noble orvalve metal. The conductive surface coating may be any material which ischemically inert to the electrolyte as well as resistant to thecorrosive conditions of the cell such as platinum group metals, alloysof platinum group metals, platinum group oxides, mixtures of paltinumgroup oxides, mixtures of paltinum group oxides and alloys which aremixtures of platinum group metal oxides with platinum group metals.Valve metal includes filmforming metals such as titanium, tantalum,zirconium, niobium and the like.

One further manipulation of float 21 is manual depression of the floatinto the mercury layer until the float rests on the mercury cathodesupport (cell bottom 13) which gives another reading on scale 26 for thedepth of the mercury layer in the electrolytic cell.

FIG. 2 shows another arrangement of the scale 26' which is mounted oncover 12 adjacent opening 15 in cover 12. Marker 24 on rod 23 poins tovalues on scale 26.

FIGS. 3A and 3B show another embodiment of the instant invention inwhich a cage 27 is used to define a chamber 22 above an opening in anode10. FIG. 3B is a partial side view of the electrolytic cell cut awayalong line B-B in FIG. 3A which is a partial top view of the cell. Againthe dimensionally stable anode shown partially cut away with workingface 11 receives power input from a source (not shown) throughappropriate lead-ins (not shown) and conductors bars (also not shown).The electrolytic cell has cell bottom 13, cell cover (not shown) andwalls (not shown) forming a substantially enclosed cell except for anopening in the cell cover enabling tube 19 to open outside the cell. Amercury reservoir 14 of given depth is supported on the mercury cathodesupport 13, forming the cathode of the cell. The anode 10 has a circularopening located at, and of diameter equal to, the distance between thetwo mesh strands labeled 16. A portion 27' of the cage is horizontal andforms the top of the cage which with four strands 27" form a chamberextending from the top of cage 27' to the working face 11 of anode 10where the strands 27" are joined with the anode 10. The strands 27" ofthe cage are fastened to anode 10 either by mechanical means or bywelding. Hollow cylindrical tube 19 is connected to the top 27' of thecage 27 and is sealed by seal 20 to the cover (as shown in FIG. 1). Thetop 27 and strands 27" of the cage enclose a chamber 22 of heightpreferably equal to the height of float 21. Float 21 is constructed soit can ride on mercury reservoir 14 and has attached rod 23 whichextends through the chamber 22, through an opening in the top 27' of thecage 27, and through tube 19 to give a reading on scale means outsidethe cell mounted on the cover. The float-rod combination is capable ofbeing movably positioned between the chamber 22 and the surface ofmercury reservoir 14. The float rod combination can be manually raisedfrom its position shown in FIG. 3B riding on the mercury reservoir 14which changes the position of a pointer on the scale means on the cover.

When rod 23 is manually raised so float 21 is in contact with the top27' of the cage 27 in chamber 22, the marker is so positioned that itindicates a zero or known calibration mark. At this position the bottomof float 21 is in a known position relative to the working face 11 ofanode 10 since the height of float 21 and the height of cavity 22 areknown values. Preferably the height of float 21 and the height of cavity22 are equal to each other so the bottom of float 21 will be even withthe work ing face 11 of anode 10 when float 21 is raised into chamber22. When rod 23 is released it moves down channel 19 as float 21 movesdown from chamber 22 into contact with mercury reservoir 14. Thisresults in rod 23 moving a marker on a scale located outside theelectrolytic cell to a new reading given the distance between theworking face 11 of anode 10 (the initial or zero reading on the scale)and the surface of the mercury reservoir 14. Where this distance variesfrom the desired distance between the working face 11 of anode 10 andmercury reservoir 14, the distance is changed by moving anode 10 to anew setting giving the desired operating distance.

While preferred embodiments of this invention have been disclosedherein, those skilled in the art will appreciate that changes andmodifications may be made therein Without departing from the spirit andscope of this invention as defined in the appended claims.

What is claimed is:

1. A method of determining the distance between the working face of ananode having an opening therein and a reservoir of mercury on a mercurycathode support beneath the anode in a substantially enclosedelectrolytic cell, where a tube in the electrolytic cell has one endattached to the anode in the region of the opening in the anode with theportion of the tube adjacent the anode being formed into a chamber ofknown height over the opening in the anode and the other end of the tubeopens outside the cover of the cell, a float of known height beingmovably disposed in the cell between the chamber and the mercuryreservoir, the float having a rod attached thereto which extends throughthe chamber and the tube to give a reading on a scale positioned outsidethe cell, said method having the steps of (a) positioning the float soit is in contact with the chamber portion of the tube which gives areading I on the scale, and

(b) releasing the float so it rides on the mercury reservoir in the cellwhich gives another reading on the scale.

2. The method of claim 1 where the anode is adjustably positioned in thecell and there is practiced the subsequent step of adjusting theposition of the anode.

3. The method of claim 1 where the movement of the float is performedwith a float of height equal to the height of the chamber above theworking face of the anode.

4. The method of claim 1 where the movement of the float is performed ina cell where the tube is welded to a structure forming a chamber ofknown height above the working face of the anode.

5. The method of claim 1 in which is practiced the additional step ofdepressing the float so it rests upon the mercury cathode support whichgives another reading on. the scale.

6. A method for determining the distance between the Working face of ananode with an opening therein and a reservoir of mercury beneath theanode in a substantially enclosed electrolytic cell, comprising thesteps of (a) positioning a tube in the electrolytic cell with one end ofthe tube attached to the anode in the region of the opening in the anodewith the portion of the tube adjacent the anode forming a chamber ofknown height over the opening in the anode and the other end of the tubeopening outside the cover of the cell, '(b) movably positioning a floatin the cell beneath the opening in the anode, the float having a knownheight, and the float having a connected stem extending through thechamber and the tube to give readings on a scale positioned outside thecell,

(c) withdrawing the float so it is in contact with the chamber portionof the tube which gives a reading on the scale, and

(d) releasing the float so it rides on the mercury reservoir in the cellwhich gives another reading on the scale.

7. The method of claim 6 in which is practiced the additional step ofdepressing the float so it rests upon the mercury cathode support whichgives another reading on the scale.

8. The method of claim 6 where the anode is adjustably positioned in thecell and there is practiced the subsequent step of adjusting theposition of the anode.

9. The method of claim 6 where the movement of the float is performedwith a float of height equal to the height of the chamber above theworking face of the anode.

10. In an electrolytic cell having an opening in the cover, an anodewith at least one opening in the working face positioned in the cell anda mercury cathode reservoir resting on a mercury cathode support, theimprovement enabling determination of the distance between the workingface of the anode and the mercury reservoir and the depth of the mercuryreservoir comprising (a) a tube connected to the opening in the cover ofthe cell and attached to the anode in the region of the opening in theanode with the portion of the tube adjacent the anode forming a chamberover the opening in the anode of known height above the working face ofthe anode,

(b) a float of known height having a rod attached thereto, the floatbeing movably disposed between the mercury reservoir and the chamberover the opening in the anode with the rod extending through the tubeand outside the cover of the cell, and

(c) scale means located on the cover outside the cell so that therelative vertical position of the float-rod combination in the cell isindicated on the scale means.

11. The electrolytic cell of claim 10 where the scale means is mountedon the cover and the rod is in contact with a pivoted pointer meansregistering a reading on the scale means.

12. The electrolytic cell of claim 10 where the scale means is mountedadjacent the opening in the cover and the rod has a pointer thereonwhich points to a reading on the scale.

13. The electrolytic cell of claim 10 where the anode is capable ofvertical displacement in the cell.

14. The electrolytic cell of claim .10 where the height of the float isequal to the height of the chamber above the working face of the anode.

15. The electrolytic cell of claim 10 in which the tube is welded to astructure forming a chamber over the opening in the anode of knownheight above the working face of the anode and the structure is weldedto the anode.

16. The electrolytic cell of claim 15 wherein the structure comprises acylindrical plug with a hole centered in the plug and the plug isthreaded around its circumference to fit into a hollow, cylindricalcoupling threaded inside to receive the plug.

17. The electrolytic cell of claim 15 where the structure comprises acage having a flat top with strands leading from the top to the anode togenerally define a chamber over the anode.

References Cited UNITED STATES PATENTS 3,480,526 11/1969 Duclaux 204-225X 3,567,615 3/1971 Nicolaisen 204-219 FOREIGN PATENTS 297,826 4/ 1954Switzerland 204-250 JOHN H. MACK, Primary Examiner D. R. VALENTINE,Assistant 'Examiner U.S. Cl. X.R. 204219, 225, 250'

